The invention relates to a device for measuring properties of a textile test specimen in a measuring gap, in which the textile test specimen is introduced, the measuring gap being formed by two walls.
Such a device is known, e.g. from EP 0 266 614. The entire disclosure of its counterpart U.S. Pat. No. 4,845,983 is incorporated herein by reference. In such devices, a measuring comb provides a plurality of measuring gaps of differing width, through which the test specimen is guided. The guiding of the test specimen in the measuring gaps is in this case effected by a thread guiding device and a forward feed device, both of which are disposed in separate and exchangeable modules, which are separable from the module with the measuring comb. The thread guiding device and the forward feed device together tension the test specimen so that it runs rectilinearly between said elements and hence also in the measuring gap. Both the thread guiding device and the forward feed device are disposed at a specific distance from the measuring gap.
A perceived drawback of the described device is that the guiding device has to be adjusted precisely in such a way that the test specimen is situated as precisely as possible in a predetermined location, e.g. in the middle of the measuring gap, when it is moved through the latter. Such adjustment of the guiding device has to be effected with great care and accuracy because, e.g. in devices intended for testing yarn, the width of a measuring gap is 1 mm or less. In addition, it is difficult with the human eye to see the conditions in the measuring gap and identify the distances there. The position of the guide or of the measuring gap has to be readjusted after each removal or installation of the module with the guide or with the measuring comb.
An object of the present invention is to provide a device of the type described, with which adjustment of the guide is simplified and with which the test specimen is nevertheless guided with sufficient accuracy.
This is achieved according to the invention by providing in the measuring gap a guide element for the test specimen, which is associated with the wall and adjusted in a stationary manner relative to said wall. The guide element is preferably firmly connected to the wall or is even part of said wall. In said case, the guide element may be placed onto the wall or inserted into the wall. It may project beyond the wall or be aligned with, i.e. not project beyond, the wall. The guide element may be disposed in such a way that it deflects the test specimen from its original path or from its direction of motion, or the measuring gap with the guide element may be aligned in such a way that the test specimen is practically not deflected.
The advantages achieved by the invention are in particular that there is no need for measures to achieve subsequent mutual alignment of the guide element and the measuring gap. The adjustment is effected once for a very long period, e.g. until the guide element presents a degree of wear by the test specimen which is significant in relation to the width of the measuring gap. The type of guidance according to the invention is suitable both for individual measuring gaps and for a plurality of adjacent measuring gaps, which together form a so-called measuring comb. The guides may be designed in such a manner that they offer as little resistance as possible to the movement of the test specimen.